Is there a Volume-Outcomes Relationship for Patients Undergoing Surgical Management of Acute Stanford Type A Aortic Dissection?

Aim: To study the world literature on patients undergoing surgical repair of acute Stanford type A aortic dissection (ATAAD). We assessed if the volume or experience of the center or surgeon affects outcomes. Methods: Literature was reviewed using the OVID platform for Medline® and Pubmed from 1966-2017. 51 papers were identified of which 12 studies met the inclusion criteria and represented the highest level of evidence to answer the research question. Results: Retrospective cohort analysis of 1550 UK patients operated on by 249 surgeons using national audit data found low volume surgeons (LVS) had higher in-hospital mortality vs high volume surgeons (HVS) (19.3% vs 12.6%, P=0.015, OR: 0.853 CI: 0.733-0.992, P=0.039), but no relationship between mortality and center volume. Five large retrospective studies using the United States (US) Nationwide Inpatient Sample (NIS) database looked at 29292 cases. Higher-volume centers (HVC) were associated with lower mortality following ATAAD repair vs lower-volume centers (LVC) (27.5% vs 16.4%, P<0.001; 34% vs 25%, P=0.003; 23.4% vs 12.1%, P=0.014; 12.6% vs 23.9%, P=0.013). A single-center cohort study in Germany, UK and three in the US reported decreased mortality after introduction of a specialized team/protocol for ATAAD repair (34.5% vs 8%, P<0.001; 33.9% vs 2.8%, P<0.0001; 33.9% vs 7.7%, P<0.0001; 22.9% vs 9.7%, P=0.002; 30.8% vs 9.7%, P=0.014). Conclusion: There is moderate evidence of a volume-outcome relationship for ATAAD surgery. This may be driven by surgeon or institutional volume. There is stronger evidence that establishing specialized multidisciplinary teams and standardized protocols reduces morbidity and mortality.